The present invention relates generally to semiconductor fabrication and more specifically to a method of forming a ring shaped electrode contact for wafer electroplating.
In the current electroplating design, a cathode electrode contact to the wafer edge is in the shape of a ring, and the seal packaging also seals the wafer edge to enclose the plating solution. This ring contact region must be free of any photoresist.
If liquid photoresist (positive and negative type) and a stepper or scanner are used, the liquid photoresist on the wafer edge can be cleared in a resist coater.
U.S. Pat. No. 5,323,535 to Sakaki et al. describes an electrical connecting member and a method of manufacturing the electrical connecting member.
U.S. Pat. No. 6,132,587 to Jornxc3xa9 et al. describes an electroplating device for wafer metallization of a wafer for interconnection and a method of electroplating for the metallization of wafers for interconnection.
U.S. Pat. No. 5,933,758 to Jain describes a method for preventing electroplating of copper on an exposed surface at the edge exclusion or a semiconductor wafer.
U.S. Pat. No. 4,273,859 to Mones et al. describes a method of forming solder bump terminals on semiconductor elements using a dry film resist process.
U.S. Pat. No. 3,591,378 to Altman describes a positive photoresist process for making photomechanical reproductions.
xe2x80x9cPhotoinitiated Polymerization,xe2x80x9d Chapter 4, Photoreactive Polymers The Science and Technology of Resists, ISBN 0-471-85550-2 Arnost Reiser, John Wiley and Sons publisher, 1988 pages 102, 103, 128, 129 and 162 to 165; describes photoinitiated polymerization, oxygen reaction with initiating radicals, and dry resist techniques.
The article xe2x80x9cDry Film Photoresists,xe2x80x9d Robert H. Wopschall, Solid State Technology, June 1986, pages 153 to 157; describes the structure and uses of dry film photoresists.
xe2x80x9cNegative Photoresists,xe2x80x9d Chapter 4, SemiConductor Lithography Principles, Practices and Materials, ISBN 0-306-42185-2, Wayne M. Moreau, Plenum Press publisher, 1987, Third Printingxe2x80x94July 1991, pages 190 to 194 and 209; describes oxygen effects in azide resists.
The excerpt from The Condensed Chemical Dictionary, Tenth Edition, revised by Gessner G. Hawley, copyright 1981, page 840, gives a definition of xe2x80x9cpolyvinyl alcohol.xe2x80x9d
The Technical Information Sheet; Poly (2-ethyl-2-oxazoline); CAS Number: 25805-17-18 available at http://www.polychemistry.com/Products/aquazol.html on the world wide web; discusses Aquazol (poly (2-ethyl-2-oxazoline)).
Accordingly, it is an object of the present invention to provide a method of clearing the dry film photoresist on a wafer edge to form a contact to the electrode of an electroplater.
It has now been discovered that the above and other objects of the present invention may be accomplished in the following manner. Specifically, a wafer having a upper exposed conductive layer is provided. The wafer having a center, an edge and a ring-shaped area proximate the wafer edge. A photoresist layer is formed upon the exposed conductive layer. The photoresist layer is removed from within the ring-shaped area by a rinse process to expose the conductive layer within the ring-shaped area. An oxygen diffusion barrier layer is formed over the photoresist layer.